A urinary catheter is a small, flexible tube that can be inserted through the urethra and into the bladder, allowing urine to drain. The urethra is the tube that carries urine from the bladder out of the body.

Standard catheters are often used for intermittent self-catheterization. A thin, flexible, hollow tube is inserted through the urethra into the bladder and allows the urine to drain out. In intermittent catheterization, the catheter is inserted, the bladder is drained, and the catheter is immediately taken out.